This invention relates to a process and to an apparatus for generating an oxidizing reagent for inter alia the treatment of polluted water and more particularly is concerned with a process and with an apparatus for generating monoperoxysulphuric ions.
It is known that the monoperoxysulphuric anion (HSO.sub.5 .sup.-) can be used for the detoxification, by oxidation, of impurities, especially cyanides, cyanhydrins, nitriles, phenols, dihydroxybenzenes, cresols, etc., contained in industrial waste water. It is also known that the monoperoxysulphuric anion can be used, either alone or in association with one or more halides, for the disinfection of water in swimming pools, reservoirs, etc. or for the sterilization of equipment such as feeding bottles, water bottles, etc. When the monoperoxysulphuric anion is used in association with one or more halides there occurs a well known reaction between the HSO.sub.5 .sup.- ion and the halide(s), which leads, depending on the pH of the medium, to the liberation of the corresponding halogen Cl.sub.2, Br.sub.2, I.sub.2 or to the formation of the corresponding hypohalites.
Commercially, the monopersulphuric anion is found either in the form of relatively stable, dilute aqueous solutions which contain, as well as HSO.sub.5 .sup.-, the HSO.sub.4 .sup.- and NH.sub.4 .sup.+ ions, or in solid form as potassium monopersulphate which is sold in admixture with potassium sulphate and potassium bisulphate. It is often advantageous, either for economic reasons or in order to avoid secondary pollution effects such as those caused by the NH.sub.4 .sup.+ ion, to employ solutions resulting from the reaction of sulphuric acid or fuming sulphuric acid on concentrated solutions of hydrogen peroxide but the monoperoxysulphuric acid solution which is obtained in this way is unstable and loses its active oxygen quickly, i.e. in a few hours.
There is therefore a need for a process and for a generator which enables one to produce the monoperoxysulphuric anion at the moment of use, i.e. before decomposition, in a quantity just sufficient to achieve the desired effect, and which permits the medium to be treated to be kept at a suitable pH value in order that the treatment can be carried out, possibly automatically, under optimum conditions.